Heat 1 tbsp olive oil in large frying pan over medium-high heat. Dust beef in seasoned flour, shaking off excess and cook in the pan in 2 to 3 batches. Cook until well browned all over and set aside. Meanwhile, heat another tablespoon of olive oil in a saucepan, add onion and garlic and cook, stirring occasionally for about 7 minutes until onion is tender. Add the browned beef, stock, Worcestershire sauce and thyme, season to taste with salt and freshly ground pepper, reduce heat to medium and simmer gently, stirring occasionally for about 45 minutes until the beef is very tender. Cool to room temperature, then divide among six individual ovenproof bowls or ramekins (about 1 cup-capacity), refrigerate to cool completely, then scatter the tops of each with a little cheddar.
Preheat oven to 180°C. Cut out rounds from the pastry large enough to overhang the sides of your dishes by about 1cm. Brush edges with a little eggwash, then place over beef mixture, eggwash side down (the eggwash will help seal the pastry to the dish). Pierce or score a hole in the top of each pie, brush pastry with eggwash and bake until for about 15 minutes until pastry is golden brown.
Meanwhile, cook peas and mint in a saucepan of boiling salted water for about 2 minutes until tender, drain, discard mint and pulse in a small food processor with butter and cream to combine. Season to taste and just before serving stir though vinegar. Spoon on top of pies and serve.
You can make the pie filling a couple of days in advance and store in an airtight container in the fridge or freeze for up to 1 month. Thaw in the freezer before using.
Instead of using chuck steak, you could use minced beef instead and stir the peas through at the end of cooking. Top with mashed potato instead of pastry and serve with a tangy tomato relish.